Dehumidifying element, dehumidifying device including dehumidifying element, and method of manufacturing dehumidifying element

ABSTRACT

A dehumidifying element includes a plurality of sheets that have moisture adsorption and desorption properties and that are stacked on top of each another. At least some of the sheets each have an irregular shape. The sheets each contain a hygroscopic agent having properties of a re-moistening-type glue that exhibits adherence when adsorbing moisture and that solidifies when being dried. The sheets are bonded to each other by the hygroscopic agent.

TECHNICAL FIELD

The present disclosure relates to a dehumidifying element, adehumidifying device including the dehumidifying element, and a methodof manufacturing the dehumidifying element. More specifically, thepresent disclosure relates to a dehumidifying element that adsorbs anddesorbs moisture in air as in dehumidifying and humidifying elements foruse in industrial, home, and automobile air conditioners and adehumidifying material for refrigerator trucks, cooling chambers,refrigerators, etc.; a dehumidifying device including the dehumidifyingelement; and a method of manufacturing the dehumidifying element.

BACKGROUND ART

In existing dehumidifying elements, planar sheets having moistureadsorption and desorption properties and corrugated sheets are bonded toeach other and stacked on top of each other by an adhesive. Such adehumidifying element using an adhesive cannot fulfill a moistureadsorption and desorption function at part of the sheets that is coatedwith the adhesive. In view of this point, in a given technique, in orderto increase the moisture adsorption effective area, bonded portions arereduced, thereby improving the performance of a dehumidifying element(for example, see Patent Literature 1).

CITATION LIST Patent Literature

-   Patent Literature 1: Japanese Patent No. 6380906

SUMMARY OF INVENTION Technical Problem

In Patent Literature 1, contact portions between the sheets haveportions that are not bonded to each other. Thus, when used in anenvironment where dry and wet conditions are repeated, the dehumidifyingelement repeatedly expands and contracts. Consequently, the portionsthat are not bonded expand, as a result of which gaps may be made in thebonded portions of the sheets. If such gaps in the bonded portions aremade at a lot of positions of a multilayer structure, air unevenly flowsin areas having gaps and areas having no gap, and as a result ahygroscopic performance becomes unstable.

The present disclosure is made to solve the above problem and relates toa dehumidifying element in which gaps are harder to form in bondedportions of sheets and that has stable hygroscopic performance, adehumidifying device including the dehumidifying element, and a methodof manufacturing the dehumidifying element.

Solution to Problem

A dehumidifying element according to an embodiment of the presentdisclosure includes multiple sheets that have moisture adsorption anddesorption properties and that are stacked on top of each other. Atleast some of the sheets each have an irregular shape. The sheets eachcontain a hygroscopic agent having properties of a re-moistening-typeglue that exhibits adherence when adsorbing moisture and that solidifieswhen being dried. The sheets are bonded to each other by the hygroscopicagent.

Advantageous Effects of Invention

Since the hygroscopic agent contained in each of the sheets hasproperties of a re-moistening-type glue according to an embodiment ofthe present disclosure, the hygroscopic agent exhibits adherence to keepthe sheets bonded to each other when adsorbing moisture, and thencontracts while keeping the sheets bonded to each other when desorbingmoisture. Thus, gaps are not easily formed in the bonded portionsbetween the sheets. In such a manner, it is possible to reduce theprobability that the gaps will be formed in the bonded portions betweenthe sheets, and thus also possible to achieve a stable hygroscopicperformance.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a dehumidifying element according toEmbodiment 1.

FIG. 2 is an enlarged schematic view of a layered body in thedehumidifying element according to Embodiment 1.

FIG. 3 is an enlarged schematic view of a first sheet of thedehumidifying element according to Embodiment 1.

FIG. 4 is an enlarged schematic view of a second sheet of thedehumidifying element according to Embodiment 1.

FIG. 5 is a view for explanation of an advantage of a hygroscopic agentof a comparative example.

FIG. 6 is a view for describing the effect of a hygroscopic agent in thedehumidifying element according to Embodiment 1.

FIG. 7 is a schematic view illustrating the flow of air in a secondsheet of the dehumidifying element according to Embodiment 1.

FIG. 8 is a flowchart of a method of manufacturing the dehumidifyingelement according to Embodiment 1.

FIG. 9 is a schematic view of the structure of a dehumidifying deviceaccording to Embodiment 2.

DESCRIPTION OF EMBODIMENTS

A preferred embodiment of a dehumidifying element will be described withreference to the drawings. In each of figures in the drawings,components that are the same as a previous figure or previous figureswill be denoted by the same reference signs.

Embodiment 1

FIG. 1 is a perspective view of a dehumidifying element according toEmbodiment 1.

A dehumidifying element 1 includes a casing 2 having a frame shape and alayered body 5 in which first sheets 3 and second sheets 4 arealternately stacked. In the casing 2, the layered body 5 is provided.The first sheets 3 and the second sheets 4 have moisture adsorption anddesorption properties. The casing 2 having a frame shape may have apolygonal, circular, or oval shape, or may have an arbitrary shape thatvaries depending on what device or apparatus the dehumidifying element 1is provided in. The material of the casing 2 can be appropriatelyselected from various materials, such as plastic, metal, or wood,according to the temperature and humidity and the flow rate of air to betreated. Preferably, in order to fix the casing 2 and the layered body 5to each other, a binder should be provided between the casing 2 and thelayered body 5.

The first sheet 3 and the second sheet 4 each contain a hygroscopicagent 6 (see FIG. 2 , which will be referred to below). Specifically,the first sheets 3 and the second sheets 4 are coated or impregnatedwith the hygroscopic agent 6. As the hygroscopic agent 6, for example, ahigh polymer compound containing polyacrylate can be applied.

The sheet base material of each of the first sheet 3 and the secondsheet 4 is pulp paper, but may be selected from other materials. Forexample, the sheet base material may be, for example, a non-woven fabricbase material made of polypropylene, polyethylene, polystyrene,polyester, or rayon. In addition, the sheet base material may be, forexample, a resin fiber non-woven fabric or metallic fiber non-wovenfabric made of metal having a high thermal conductivity, such asaluminum or copper.

The first sheet 3 and the second sheet 4 each containing the hygroscopicagent 6 are formed of, for example, a sheet non-woven fabric including aresin fiber mixed with the hygroscopic agent 6, or paper incorporatingthe hygroscopic agent 6. The following are examples of the method ofcausing the first sheet 3 and the second sheet 4 to contain thehygroscopic agent 6: in the case where the hygroscopic agent 6 is in adispersion state or a solution state, a sheet base material is coatedwith the hygroscopic agent 6; and a sheet base material, which is, forexample, paper or non-woven fabric, is impregnated with the hygroscopicagent 6. When being in the form of fiber, the hygroscopic agent 6 itselfis used as a fiber that forms paper or non-woven fabric and is mixedwith another fiber, whereby the other fiber contains the hygroscopicagent 6.

In order to improve the hygroscopic performance of the first sheets 3and the second sheets 4 and bond layers which will be described later toeach other, preferably, the first sheets 3 or the second sheets 4, orthe first sheets 3 and the second sheets 4, should entirely contain thehygroscopic agent 6. In the case where the entire sheets contain thehygroscopic agent 6, when the layered body 5 is formed, the content ofhygroscopic agent 6 per unit volume will increase, and the hygroscopicproperties of the layered body 5 will be improved. Furthermore, asdescribed below, the hygroscopic agent 6 adsorbs moisture in ahigh-humidity environment and exhibits adherence. Thus, in the casewhere the entire sheets contain the hygroscopic agent 6, the contactarea between the sheets increases, and the entire contact portions canbe bonded to each other. As a result, the layered body 5 becomes a morestrongly bonded state.

FIG. 2 is an enlarged schematic view of the layered body in thedehumidifying element according to Embodiment 1. FIG. 3 is an enlargedschematic view of a first sheet of the dehumidifying element accordingto Embodiment 1. FIG. 4 is an enlarged schematic view of a second sheetof the dehumidifying element according to Embodiment 1.

In the dehumidifying element 1, the first sheets 3 and/or the secondsheets 4 have an irregular shape. FIG. 2 illustrates by way example thefirst sheets 3 have an irregular shape and the second sheets 4 have aplanar shape. Since the first sheets 3 and the second sheets 4 arealternately stacked on top of each other, voids are formed between thesheets and serve as air passages 5 a through which air passes. Thelayered body 5 is provided in the casing 2 such that a surface of thelayered body 5 from which the air passages 5 a between the sheets areviewed is located at an opening surface of the casing 2.

As the hygroscopic performance of the first sheets 3 and the secondsheets 4, at a relative humidity of 60% RH and at 20 degrees C.,preferably, the first sheets 3 and the second sheets 4 should adsorb 10g or more of moisture per square meter, and more preferably shouldadsorb 20 g or more of moisture per square meter. The hygroscopic agent6 is partially water-soluble, and for example, satisfactorily adsorbsmoisture in air at a relative humidity of 60% RH or more and at 20degrees C. When the hygroscopic agent 6 adsorbs much moisture, thisinduces adherence and the hygroscopic agent thus exhibits adherence atthe sheet surfaces. At a relative humidity of less than 60% RH, thehygroscopic agent 6 desorbs moisture and solidifies. When thehygroscopic agent 6 desorbs moisture, the adherence of the sheetsurfaces is reduced to a low level. As described above, the hygroscopicagent 6 contains a re-moistening-type glue that exhibits adherence whenadsorbing moisture and that solidifies and exhibits low adherence whendesorbing moisture. The above values of the temperature, humidity, andother parameters are described as appropriate values, and thesedescriptions are not limiting.

In the case where the dehumidifying element 1 is applied to airconditioners, it is preferable that the humidity of an indoor space beadjusted to 40% to 60% RH. It is therefore easy to adjust the humidityof the indoor space by using, in the dehumidifying element 1, ahygroscopic agent 6 having a property of adsorbing much moisture at ahumidity of 60% RH or higher.

The hygroscopic agent 6 is partially water-soluble as described above.It will be described what advantage is obtained by the partiallywater-soluble hygroscopic agent 6 with reference to FIGS. 5 and 6 .

FIG. 5 is a view for explanation of an advantage obtained by ahygroscopic agent of a comparative example. FIG. 6 is a view forexplanation of an advantage obtained by a hygroscopic agent in thedehumidifying element according to Embodiment 1.

A hygroscopic agent 60 that is hard and is not water-soluble has a pooranchoring effect on each of surfaces of a sheet 30 and a sheet 40 asillustrated in FIG. 5 . By contrast, as illustrated in FIG. 6 , thehygroscopic agent 6 according to Embodiment 1 is shaped to fit to theirregularities of the surface of each of the first sheet 3 and thesecond sheet 4 when the hygroscopic agent 6 adsorbs moisture andpartially dissolves in it, and has thus a great anchoring effect on thesurfaces. As a result, the hygroscopic agent 6 obtains a great adhesiveeffect when being dried.

Specifically, the partially water-soluble hygroscopic agent 6 has, forexample, the following structure. The hygroscopic agent 6 is across-linked polyacrylate and includes a mixture of a polymer having adegree of crosslinking that corresponds to 0.2 mol % or less of acrosslinking agent to the monomer and a polymer having a degree ofcrosslinking that corresponds to higher than 0.2 mol % of thecrosslinking agent to the monomer. The degree of crosslinking is thepercentage of a polymer that remains after solvent immersion relative tothe initial polymer.

Hydration related to water solubility occurs mainly near hydrophilicgroups. The lower the percentage of cross-linked parts in the totalpolymers, the higher the percentage of hydrated parts in the totalpolymers, and the higher the water solubility. The lower the percentageof cross-linked parts, the less the polymer network structure, and thesmaller the molecular weight. For example, a polymer having a molecularweight of 10,000,000 or less is easily dissolved in water when thepolymer surface is hydrated. Thus, when the number of cross-linked partsis small, the molecular weight decreases and the water solubility may beimproved.

As the amount of crosslinking agent increases, and the percentage ofcross-linked parts increases, the water solubility decreases, but themoisture retention is improved. Since polymers having high moistureretention also have high hygroscopicity, the hygroscopic agent 6 is alsomade to contain a polymer having a high crosslinking agent content.

When a salt is prepared from a divalent and higher valent metal, such asan alkaline-earth metal, intermolecular cross-linking occurs to causegelation. The gelation may deteriorate the hygroscopicity and the watersolubility, which are important for the dehumidifying element 1. Thepolyacrylate for use in the hygroscopic agent 6 is a polymer produced bypolymerizing a monomer component containing an acrylate. It ispreferable that the acrylate be an alkali metallic salt, such aslithium, sodium, potassium, rubidium, or cesium, or an ammonium salt.The salt for use in the hygroscopic agent 6 may be a mono-, di-, ortri-alkyl or hydroxyalkyl ammonium salt, a polyvalent metal salt, or acombination of these salts. With regard to neutralization of carboxylgroups, an acrylic acid may be neutralized into an acrylate beforepolymerization, or a polyacrylic acid during or after polymerization maybe neutralized into a polyacrylate. Alternatively, these methods may beused in combination.

With regard to neutralization, an unneutralized carboxyl group, or apolyacrylic acid, may be neutralized with a base, or a neutralizedcarboxyl group, or a polyacrylate, may be neutralized with an acid. Thefollowing are examples of the acid or base for use in suchneutralization: hydroxides of alkali metals or ammonia; various bases,such as carbonates or bicarbonates; and various acids, such ashydrochloric acid or sulfuric acid. In addition, as a method other thanneutralization, an acid and a salt of carboxyl group may be convertedusing an ion exchange resin. By applying such a method, the polyacrylateis converted into a salt of an alkali metal, such as lithium, sodium,potassium, rubidium, or cesium, or an ammonium salt.

The hygroscopic agent 6 contains a partially cross-linked water-solubleacrylate as described above. The following are examples of thecrosslinking component in such a partially cross-linked water-solubleacrylate: monomers having reactive groups, such as ethylene glycoldimethacrylate, trimethylolpropane trimethacrylate, ethylene glycoldiacrylate, trimethylolpropane triacrylate, glyceryl trimethacrylate,glyceryl triacrylate, divinylbenzene, N-methylolacrylamide, glycidylmethacrylate, methacrylic acid, acrylic acid, linoleic acid,hydroxyethyl methacrylate, and hydroxyethyl acrylate.

The following are examples of the component to be copolymerized withthese crosslinking components: methyl methacrylate; methyl acrylate;ethyl methacrylate; ethyl acrylate; butyl methacrylate; butyl acrylate;2-ethylhexyl acrylate; 2-ethylhexyl methacrylate; styrene;N-isopropylacrylamide; N,N-dimethylacrylamide;N,N-dimethylaminomethylacrylamide; N,N-dimethylaminopropylacrylamide;vinyl methyl ether; vinyl ethyl ether, vinyl isopropyl ether,vinylpyrrolidone; vinyl acetate; maleic anhydride; sodium acrylate;ammonium acrylate; sodium stearate; ammonium stearate; and stearic acidamide.

As the polymerization catalyst in this case, a persulfate, such asammonium persulfate, potassium persulfate or sodium persulfate can begenerally used, and in addition, for example, benzoyl peroxide orazobisisobutyronitrile can be used.

In the dehumidifying element 1 having the above structure, when moistair enters the casing 2 and passes through the air passages 5 a formedbetween the first sheets 3 and the second sheets 4, moisture in the airis adsorbed by the hygroscopic agent 6 contained in each of the firstsheets 3 and the second sheets 4. As a result, the air is dehumidified,and the dehumidified air flows out of the casing 2. When dry air entersthe casing 2 and passes through the air passages 5 a formed between thefirst sheets 3 and the second sheets 4, moisture adsorbed by thehygroscopic agent 6 contained in each of the first sheets 3 and thesecond sheets 4 is given to the air passing through the air passages 5a. As a result, the air is humidified, and the humidified air flows outof the casing 2.

The dehumidifying element 1 expands and contracts as the hygroscopicagent 6 adsorbs and desorbs moisture. If the bonded portions between thesheets are not resistant to a stress that acts because of expansion andcontraction of the dehumidifying element 1, the sheets may be broken, orgaps may be formed in the bonded portions between the sheets. InEmbodiment 1, however, the hygroscopic agent 6 contains are-moistening-type glue and thus exhibits adherence at a humidity (60%RH or higher in this case) at which much moisture is adsorbed. Thus, thebonded state of the sheets is weakened while the sheets are kept incontact with each other, and the sheets can slightly move relative toeach other at the bonded portions. It is therefore possible to reducethe stress that acts because of expansion and contraction of thedehumidifying element 1 and reduce the probability with which the sheetsmay be broken and gaps are formed between the sheets.

It is preferable that the first sheets 3 and the second sheets 4 haveair permeability. In other words, it is preferable that the first sheets3 and the second sheets 4 have fine voids in the sheets, and air diffusethrough the voids and pass through the sheets themselves. This pointwill be described with reference to FIG. 7 by referring to the secondsheet 4, which is illustrated in FIG. 7 . However, the same is true ofthe first sheet 3.

FIG. 7 is a schematic view illustrating the flow of air in the secondsheet of the dehumidifying element according to Embodiment 1. In FIG. 7, arrows indicate the flow of air.

In the case where the second sheet 4 itself have voids, air diffusesthrough the voids in the second sheet 4 and comes into contact with thehygroscopic agent 6 on the surface of a fiber 7 in the second sheet 4,whereby moisture in the air is adsorbed by the hygroscopic agent 6, asillustrated in FIG. 7 . That is, since the air diffuses through thevoids in the second sheet 4, the contact surface between the air and thehygroscopic agent 6 is larger than in the case where air cannot passthrough the second sheet 4. Thus, the hygroscopic performance of thesecond sheet 4 is improved, and the hygroscopic properties are thussatisfactory. It should be noted that the above description refers toadvantages obtained at the time at which moisture is adsorbed; however,the same advantages as described above are obtained at the time ofdrying, and the drying performance is improved. Since the sheetsthemselves have the air permeability, it is possible to increase amoisture adsorption rate and a drying rate of the dehumidifying element1 as a whole. In order to efficiently support the hygroscopic agent 6 onthe surface of the fiber 7, preferably, the fiber 7 should have higherwettability. Also, preferably, a hydrophilic fiber should be used as thefiber 7, or the fiber 7 should be hydrophilized.

As described above, it is preferable that the sheets have airpermeability, and at least one of the first sheet 3 and the second sheet4 have the lowest possible air resistance and the highest possible airflow rate. The permeation rate of air into the sheets is evaluated asthe air permeance rate or air resistance defined in, for example, JISP-8117:2009 and TAPPI T460 cm-02. Specifically, it is preferable that atleast one of the first sheet 3 or the second sheet 4 have an airresistance of 5000 sec/100 cc or less as a value measured by a highpressure densometer.

As described above, the dehumidifying element 1 of Embodiment 1 includesa plurality of sheets that have moisture adsorption and desorptionproperties and that are stacked on top of each other, and at least someof the sheets each have an irregular shape. The sheets each contain ahygroscopic agent 6 having properties of a re-moistening-type glue thatexhibits adherence when adsorbing moisture and that solidifies whenbeing died. The sheets are bonded to each other by the hygroscopic agent6.

Since the hygroscopic agent 6 contained in each of the sheets hasproperties of a re-moistening-type glue, the hygroscopic agent 6exhibits adherence to keep the sheets bonded to each other whenadsorbing moisture, and then contracts while keeping the sheets bondedto each other when desorbing moisture. Therefore, gaps are not easilyformed in the bonded portions between the sheets. Since it is possibleto reduce the probability that gaps will be formed in the bondedportions between the sheets, and thus reduce an uneven flow of airthrough the dehumidifying element 1 and can obtain a stable hygroscopicperformance. The hygroscopic agent 6 exhibits adherence when adsorbingmoisture, and the sheets can slightly move relative to each other in thebonded portions. It is therefore possible to weaken a stress that actsbecause of expansion and contraction of the dehumidifying element 1. Asa result, it is possible to reduce the probability that the sheets willbe broken and gaps will be formed between the sheets, and thus provide adehumidifying element 1 having high durability.

In the dehumidifying element 1 of Embodiment 1, sheets having anirregular shape and sheets having a planar shape are alternately stackedon top of each other.

As described above, the layered body 5 having a stack of multiple sheetshas a structure in which sheets having an irregular shape and sheetshaving a planar shape are alternately stacked.

The hygroscopic agent 6 contains a water-soluble polyacrylate.

Since the hygroscopic agent 6 contains a water-soluble polyacrylate asdescribed above, the hygroscopic agent 6 fits between the sheet basematerials when adsorbing moisture and improves the anchoring effect,whereby the sheets can be strongly bonded to each other. Thewater-soluble polyacrylate exhibits high moisture adsorption and thusimproves the hygroscopic properties of the dehumidifying element 1.

The base materials of the sheets are each a non-woven fabric of pulp,resin fiber, or metal fiber, and have air permeability.

Since each of the base material has air permeability as described above,air diffuses through the base material, and the contact area between theair and the hygroscopic agent 6 contained in the base material thusincreases, whereby the moisture adsorption rate and the drying rateduring drying can be increased.

<Method of Manufacturing Dehumidifying Element>

Next, a method of manufacturing the dehumidifying element 1 will bedescribed.

FIG. 8 is a flowchart of a method of manufacturing the dehumidifyingelement according to Embodiment 1.

The dehumidifying element 1 is manufactured through steps indicated inFIG. 8 . First, a plurality of sheets are each caused to contain ahygroscopic agent 6 containing a re-moistening-type glue (step S1).Then, some of the sheets are processed to have an irregular shape (stepS2). The order in which step S1 and step S2 are carried out may bereversed. In other words, the sheets may be each caused to contain thehygroscopic agent 6 before or after some sheets are processed to have anirregular shape. Which of the orders in which the above steps arecarried out is selected can be determined in consideration of theprocessability of sheet-like materials having moisture adsorption anddesorption properties, the processability for attaching a moistureadsorbing and desorbing agent, and other factors. In the followingdescription, sheets processed to have an irregular shape in step S2 arereferred to as first sheets 3, and other sheets are referred to assecond sheets 4.

Subsequently, the re-moistening-type glue is caused to exhibitadherence, and the first sheets 3 and the second sheets 4 are stacked ontop of each other to form a layered body 5 (step S3). As the method offorming the layered body 5, the following two methods are provided: amethod in which the first sheets 3 processed to have an irregular shapeand the second sheets 4 are stacked in turn one by one (this method willbe hereinafter referred to as a stacking method 1); and a method inwhich the first sheets 3 and the second sheets 4 are stacked after beingsubjected to bonding processing (this method will be hereinafterreferred to as a stacking method 2).

(Stacking Method 1)

In the method in which the first sheets 3 processed to have an irregularshape and the second sheets 4 are stacked in turn one by one, steam issprayed on a first sheet 3, or water is applied to a surface of thefirst sheet 3 with a brush or other tool. In such a manner, whenmoisture is given to the first sheet 3, the surface of the first sheet 3exhibits adherence, and a second sheet 4 is stacked on the first sheet3. At this time, when steam is sprayed on the second sheet 4 or whenwater is applied to a surface of the second sheet 4 with a brush orother tool, the surface of the second sheet 4 can also exhibitadherence, and it is therefore possible to achieve stronger bonding.Thus, it is preferable that steam be also sprayed on the second sheet 4or water be also applied to the surface of the second sheet 4 with abrush or other tool.

Subsequently, steam is sprayed on or water is applied to, with a brushor other tool, a surface of the second sheet 4 that is opposite to asurface bonded to the first sheet 3, and a first sheet 3 is then stackedon the second sheet 4. This step is repeatedly carried to form thelayered body 5. Since these sheets exhibit adherence at a relativehumidity of 60% RH or more as described above, the step of sprayingsteam or the step of applying water to the surface with a brush or othertool can be omitted by maintaining a high humidity in the environment atthe stacking time.

(Stacking Method 2)

In the method in which the first sheets 3 and the second sheets 4 arestacked on top of each other after being subjected to the bondingprocessing, an adhesive is applied to distal ends of protrusions of afirst sheet 3 having an irregular shape and the surrounding areas of thedistal ends, and the first sheet 3 and a second sheet 4 are bonded toeach other. Preferably, the adhesive should have high adhesiveness. Thefollowing are examples of the adhesive: a silicone caulking agent; epoxyresin; vinyl acetate resin; an acrylic adhesive; polyvinylpyrrolidone;poval; and starch paste. Next, multiple bonded bodies each obtained bybonding a first sheet 3 and a second sheet 4 to each other are stackedon top of each other. In the case of stacking bonded bodies, steam issprayed on or water is applied to, with a brush or other tool, a surfaceof a sheet of a bonded body, and another bonded body is stacked on andbonded to the former bonded body. Alternatively, multiple bonded bodiesare stacked on top of each other in a high-humidity environment. As aresult, the layered body 5 is formed.

After the step of forming the layered body 5 as described above, thelayered body 5 is dried to solidify the re-moistening-type glue of thehygroscopic agent 6 on the sheet surfaces (step S4) and thus to reducethe adherence of the sheet surfaces. The sheets are thus bonded andfixed to each other. The layered body 5 in which the sheets are fixed isplaced in the casing 2.

The dehumidifying element 1 is formed through the steps described above.In the case where a binder is applied between the casing 2 and thelayered body 5, the layered body 5 may be placed in the casing 2 beforethe drying step, and be dried together with the binder.

A stack of the first sheet 3 and the second sheet 4 has, for example, asingle-face corrugated board shape. In a method of forming a single-facecorrugated board shape, the first sheet 3 is corrugated by inserting amaterial paper, using a corrugating machine, or a rack and a pinion,between the first sheet 3 and the corrugating machine or the rack andpinion. The second sheet 4 having a planar shape is stacked on the firstsheet 3 while maintaining the planar shape, thereby combining a planarshape and a corrugated shape, and forming a single-face corrugatedcardboard shape. In such a manner, in the dehumidifying element 1 ofEmbodiment 1, it suffices that at least one of the first sheet 3 and thesecond sheet 4 is processed to have an irregular shape, and the shapeobtained by the processing of forming an irregular shape is not limitedto the corrugated shape. As this processing, for example, knurling withan embossing roller or other roller may be applied.

In the above example, only one of the first sheet 3 and the second sheet4 is processed to have an irregular shape. However, both the sheets 3and 4 may be processed to have an irregular shape. In the case where thesheets 3 and 4 are both processed to have an irregular shape, the sheetsare stacked such that recesses and protrusions of one sheet do notoverlap with those of another sheet. In an example of the sheets bothprocessed to have an irregular shape, it is conceivable that the firstsheet 3 and the second sheet 4 are corrugated or knurled, and when thefirst and second sheets 3 and 4 are stacked, one of the first and secondsheets 3 and 4 is inclined such that the recesses and protrusions of theabove one sheet do not overlap with those of the other sheet. It shouldbe noted that in the case of stacking sheets both processed to have anirregularly shape, in general, it is hard to define contact portionsbetween the sheets and also hard to apply an adhesive at importantpositions to fix the sheets. By contrast, in the dehumidifying element 1of Embodiment 1, the hygroscopic agent 6 containing a re-moistening-typeglue is supported at the entire sheets. Thus, by moistening thehygroscopic agent 6 and stacking and drying the sheets, the contactportions between the sheets are bonded and fixed to each other. Thus, itis not necessary to apply an adhesive, and the workability is improved.

Embodiment 2

Embodiment 2 relates to a dehumidifying device including thedehumidifying element 1 of Embodiment 1.

FIG. 9 is a schematic view of a configuration of a dehumidifying deviceaccording to Embodiment 2.

A dehumidifying device 8 including a casing 8 a in which a first inlet10, a first outlet 11, a second inlet 12, and a second outlet 13 areformed. The first inlet 10 is connected with an outside air duct 16. Thefirst outlet 11 is connected with a supply air duct 17. The second inlet12 is connected with a return air duct 18. The second outlet 13 isconnected with an exhaust air duct 19.

In the casing 8 a, a supply air passage and an exhaust air passage areprovided independent of each other. The supply air passage is an airpassage through which the first inlet 10 communicates with the firstoutlet 11. The exhaust air passage is an air passage through which thesecond inlet 12 communicates with the second outlet 13. In the supplyair passage, a supply air fan 15 and a first dehumidifying element 1Aare provided. In the exhaust air passage, an exhaust air fan 14 and asecond dehumidifying element 1B are provided. The first dehumidifyingelement 1A and the second dehumidifying element 1B are each thedehumidifying element 1 of Embodiment 1.

In the dehumidifying device 8 having the above configuration, when thesupply air fan 15 is driven, a first fluid flows from an outdoor spaceinto the outside air duct 16 and then flows into the supply air passagethrough the first inlet 10. The first fluid that has flowed into thesupply air passage passes through the first dehumidifying element 1A,then flows out from the first outlet 11 and is supplied into the indoorspace through the supply air duct 17. In the above case, in the supplyair passage, when the first fluid passes through the first dehumidifyingelement 1A, moisture contained in the first fluid is adsorbed by thefirst dehumidifying element 1A, whereby the first fluid is dehumidifiedand the first dehumidifying element 1A is humidified. The dehumidifiedfirst fluid is supplied into the indoor space.

When the exhaust air fan 14 is driven, a second fluid flows from theindoor space into the return air duct 18 and then flows into the exhaustair passage through the second inlet 12. The second fluid that hasflowed into the exhaust air passage passes through the seconddehumidifying element 1B, then flows out from the second outlet 13 andis discharged to the outdoor space through the exhaust air duct 19. Inthe above case, in the exhaust air passage, when the second fluid passesthrough the second dehumidifying element 1B, moisture contained in thesecond dehumidifying element 1B is given to the second fluid, wherebythe second fluid is humidified and the second dehumidifying element 1Bis dried.

In the casing 8 a, an air-passage switching member such as a damper (notillustrated) that performs switching between the air passages isprovided. To be more specific, the switching between the air passages isperformed such that the first fluid that flows through the supply airpassage passes through the second dehumidifying element 1B and thesecond fluid that flows through the exhaust air passage passes throughthe first dehumidifying element 1A.

Therefore, when the supply air fan 15 is driven, the first fluid flowsfrom the outdoor space into the outside air duct 16, and then flows intothe supply air passage through the first inlet 10. The first fluid thathas flowed into the supply air passage passes through the seconddehumidifying element 1B, then flows out from the first outlet 11, andis supplied into the indoor space through the supply air duct 17. In theabove case, in the supply air passage, when the first fluid passesthrough the second dehumidifying element 1B, moisture contained in thefirst fluid is adsorbed by the second dehumidifying element 1B, wherebythe first fluid is dehumidified and the second dehumidifying element 1Bis humidified. The dehumidified first fluid is supplied into the indoorspace.

When the exhaust air fan 14 is driven, the second fluid flows from theindoor space into the return air duct 18, and then flows into theexhaust air passage through the second inlet 12. The second fluid thathas flowed into the exhaust air passage passes through the firstdehumidifying element 1A, then flows out from the second outlet 13, andis discharged to the outdoor space through the exhaust air duct 19. Inthe above case, in the exhaust air passage, when the second fluid passesthrough the first dehumidifying element 1A, moisture contained in thefirst dehumidifying element 1A is given to the second fluid, whereby thesecond fluid is humidified and the first dehumidifying element 1A isdried.

As described above, when the switching between the air passages isperformed, humidification and drying processes are reversed such thatbefore the switching, the first dehumidifying element 1A is humidifiedand the second dehumidifying element 1B is dried, and after theswitching, the first dehumidifying element 1A is dried and the seconddehumidifying element 1B is humidified.

The switching between the air passages is performed at regularintervals. As a result, humidification and drying of each of thedehumidifying elements are alternately repeated, thereby enabling adehumidification operation to be continuously performed.

The dehumidifying device 8 of Embodiment 2 includes the dehumidifyingelement 1 of Embodiment 1, and can thus achieve a stable hygroscopicperformance.

REFERENCE SIGNS LIST

1: dehumidifying element, 1A: first dehumidifying element, 1B: seconddehumidifying element, 2: casing, 3: first sheet, 4: second sheet, 5:layered body, 5 a: air passage, 6: hygroscopic agent, 7: fiber, 8:dehumidifying device, 8 a: casing, 10: first inlet, 11: first outlet,12: second inlet, 13: second outlet, 14: exhaust air fan, 15: supply airfan, 16: outside air duct, 17: supply air duct, 18: return air duct, 19:exhaust air duct, 30: sheet, 40: sheet, 60: hygroscopic agent

1. A dehumidifying element using a layered body in which a plurality ofsheets each containing a hygroscopic agent and having moistureadsorption and desorption properties are stacked on top of each other,and at least some of the sheets each have an irregular shape, thedehumidifying element comprising: a casing having a frame shape andholding the layered body; and a binder fixing the layered body in thecasing, wherein the binder is different from the hygroscopic agent, thehygroscopic agent has properties of a re-moistening-type glue thatexhibits adherence when adsorbing moisture and that solidifies whenbeing dried, and the hygroscopic agents bonds the plurality of sheets toeach other, and the hygroscopic agent is a crosslinked polyacrylate andincludes a mixture of a polymer having a degree of crosslinking thatcorresponds to 0.2 mol % or less of a crosslinking agent to a monomerand a polymer having a degree of crosslinking that corresponds to higherthan 0.2 mol % of the crosslinking agent to the monomer.
 2. Thedehumidifying element of claim 1, wherein in the plurality of sheets,the sheets each having the irregular shape and sheets each having aplanar shape are alternately stacked on top of one another.
 3. Thedehumidifying element of claim 1, wherein the hygroscopic agent containsa water-soluble polyacrylate.
 4. The dehumidifying element of claim 1,wherein base materials of the plurality of sheets are each a non-wovenfabric of pulp, resin fiber, or metal fiber, and have air permeability.5. A dehumidifying device comprising the dehumidifying element ofclaim
 1. 6. A method of manufacturing a dehumidifying element,comprising: causing each of a plurality of sheets to contain ahygroscopic agent containing a re-moistening-type glue; processing someof the plurality of sheets to cause each of the some sheets to have anirregular shape; forming a layered body by bonding the plurality ofsheets to each other, the bonding of the plurality of sheets beingachieved by moistening each of the plurality of sheets to cause there-moistening-type glue in the sheet to exhibit adherence; and dryingthe layered body to solidify the re-moistening-type glue, preparing acasing having a frame shape, fixing the dried layered body in the casingusing a binder that is different from the hygroscopic agent, andpreparing, as the hygroscopic agent, an admixture that is a crosslinkedpolyacrylate and includes a mixture of a polymer having a degree ofcrosslinking that corresponds to 0.2 mol % or less of a crosslinkingagent to a monomer and a polymer having a degree of crosslinking thatcorresponds to higher than 0.2 mol % of the crosslinking agent to themonomer.
 7. The method of manufacturing a dehumidifying element of claim6, wherein in the forming the layered body, in the plurality of sheets,the sheets each caused to have the irregular shape and sheets eachhaving a planar shape are stacked on top of each other.
 8. The method ofmanufacturing a dehumidifying element of claim 6, wherein a hygroscopicagent containing a water-soluble polyacrylate is used as the hygroscopicagent.
 9. The method of manufacturing a dehumidifying element of claim6, wherein base materials of the plurality of sheets are each anon-woven fabric of pulp, resin fiber, or metal fiber, and have airpermeability.